Polyester resin for toner, process for its production and toner

ABSTRACT

A polyester resin for toner comprising an acid component containing at least one selected from the group consisting of aromatic dicarboxylic acids and their lower alkyl esters, and an alcohol component containing at least one selected from the group consisting of bisphenol A derivative diols, wherein the content of aldehyde compounds, their decomposition products and by-products in the polyester resin is no more than 200 ppm. Toner polyester resins and toners are obtained which do not generate irritating odors even upon melting and kneading during the toner production or upon heating during the copying process, which provide clear images with no haziness due to reduced light permeability of the copy material, which have a wide range of color tone reproduction, and which provide excellent image precision on copied print.

TECHNICAL FIELD

The present invention relates to a polyester resin which is useful asdry toner resin to be used for developing electrostatic charged imagesor magnetic latent images by electrophotography, electrostaticrecording, electrostatic printing, etc., as well as to a process for itsproduction and use. More specifically, the present invention relates toa polyester resin for full color toner which is useful in cases whereimage clarity and precision are required, as well as a process for itsproduction and toner employing it.

BACKGROUND ART

Methods of obtaining perpetual clear images through electrostatic chargeinvolve developing an electrostatic charged image formed on anelectrophotosensitive material or electrostatic recording medium, usingtoner which has previously been electrostatically charged by friction,and then fixing the image. In the case of magnetic latent images, alatent image on a magnetic drum is developed by toner containing amagnetic substance, and then fixed.

The fixing is accomplished either by direct fusion of a developed tonerimage onto an electrophotosensitive material or electrostatic recordingmedium, or by transferring a toner image onto paper or film and thenfusing it onto a transfer sheet. The toner fusion is accomplished bycontact with a solvent vapor, or by pressure and heat. The heatingsystem may be either a non-contact heating system employing anelectrical oven or a contact heating system employing a contact roller,but the latter has been mainly used in recent years due to demand for afaster fixing process.

Toner used in dry developing processes include one-component toner andtwo-component toner. To prepare a two-component toner, first a resin,coloring agent, charge controller and other necessary additives aremelted, kneaded and made into a thorough dispersion which is coarselyand then finely crushed, and sorted into prescribed grain size ranges. Aone-component toner is prepared in the same manner, though with additionof magnetic iron powder to each of the components of the above-mentionedtwo-component toner.

The resin, being the major component of the toner mixture, isresponsible for most of the required performance of the toner. Thus, fortoner production, toner resins must have good dispersability in thecoloring agent during the melting/kneading process and good crushabilityduring the crushing process, and for toner use they require a variety ofproperties, including satisfactory fixation properties, non-offsettingproperties, blocking resistance and electrical qualities.

Publicly known resins used for toner production include epoxy resins,polyester resins, polystyrene resins, methacrylic resins and the like,but contact heat fixation systems primarily use styrene and(meth)acrylic acid ester copolymers. Recently, however, attention hasbeen focused on polyester resins because they allow fixation at evenlower temperatures and provide excellent polyvinyl plasticizerresistance for the fixed toner images.

Also, in order to obtain color images, the colors must be produced andfixed by adhering 3- or 4-color toner onto transfer paper during thedeveloping process described above, and then melting and mixing each ofthe components in the fixing process. It is strongly preferred, asmentioned above, that binder resins for full color toner have goodmixability during the fixing process, i.e., good melt flowability.However, using binder resins with satisfactory melt flowability resultsin the problem of an offsetting phenomenon during the fixing process.

Although this offsetting phenomenon may be prevented by crosslinking thebinder resin to induce polymerization, such a measure lowers its meltflowability and thus renders it unsuitable as a binder resin for fullcolor toner. Consequently, in order to prevent offsetting when usingfull color copiers, silicone oil or the like is applied onto the surfaceof the fixing roller.

In addition, recent emphasis has been placed not only on imageproperties but also on environmental factors, and the generation ofirritating odors during toner production and during copying has led to anumber of problems with operators and at offices. Furthermore, sincefull color toners are often used for copying to OHP sheets, the problemresults that the permeability of the copy material is lowered when thebinder resin is colored, and the image is hazy when projecting by OHP.Moreover, coloring of binder resins when using full color tonersemploying a mixture of the 3 primary colors cyan, magenta and yellow,results in a narrow range of color tone reproduction, and thus lowerimage precision of the copied print. Thus, under the presentcircumstances in which even higher image precision is in demand, binderresins are now required which have high performance, i.e., low odor andlow coloring.

DISCLOSURE OF THE INVENTION

It is an object of the present invention, having been accomplished underthe situation described above, to provide a polyester resin for tonerwhich provides excellent image precision on copied print withoutgenerating irritating odors during production or use of the toner,providing clear images with no haziness due to lower permeability of thecopy material, and having a wide range of color tone reproduction.

As a result of intensive research aimed at achieving the aforementionedobject, the present inventors have completed the present invention uponthe finding that such object may be achieved with a polyester resinwherein the content of aldehyde compounds, their decomposition productsand their by-products is within a specific numerical limit,

In other words, the present invention is a polyester resin for tonerwhich comprises an acid component containing at least one selected fromthe group consisting of aromatic dicarboxylic acids and their loweralkyl esters, and an alcohol component containing at least one selectedfrom the group consisting of bisphenol A derivative diols, the contentof aldehyde compounds, their decomposition products and theirby-products in the polyester resin being no more than 200 ppm.

The polyester resin of the invention is useful as a binder resin for drytoner used for the developing of electrostatic charged images ormagnetic latent images by electrophotography, electrostatic recording,electrostatic printing, and the like.

BEST MODE FOR CARRYING OUT THE INVENTION

Aldehyde compounds, their decomposition products and their by-productsaccording to the invention are compounds, decomposition products andby-products which have acetaldehyde, propionaldehyde or other aldehydegroups and have boiling points no higher than 180° C.

These aldehyde compounds, decomposition products and by-products areproduced by heat-induced decomposition of bisphenol A derivativecomponents used in toner polyester resins, or by reductive reaction ofcarboxylic acids which is essential for polyesters. The aldehydecompounds, decomposition products and by-products can result through avariety of processes for polyester resin-based toner. The aldehydecompounds and their decomposition products can also yield dioxalanecompounds by reaction with starting materials for polyesters, such asethylene glycol.

These aldehyde compounds, their decomposition products and by-productscan adversely affect the coloring of the polyester resins mentionedabove, and can also be a cause of irritating odor from the toner. Inparticular, compounds with low boiling points such as acetaldehydes andpropionaldehydes tend to be easily dispersed in the air upon heatingduring the melting and kneading of toner production, or during copying,thus resulting in irritating odors.

Therefore, it is important that the content of aldehyde compounds, theirdecomposition products and by-products in the polyester resin employedin the toner or in the toner itself be in a range of no greater than 200ppm, preferably 100 ppm, more preferably no greater than 50 ppm, andeven more preferably no greater than 10 ppm. This is because whenaldehyde compounds, their decomposition products and by-products arepresent in the polyester resin or toner at greater than 200 ppm, theytend to adversely affect the coloring of the polyester resin and alsocreate an irritating odor in the toner.

The toner polyester resin of the invention preferably has a lightabsorbance of no greater than 0.05 at a wavelength of 440 nm. This isbecause when the absorbance value is greater than 0.05 the lightpermeability is lowered making it impossible to obtain clear images whenused as a full color toner binder resin for copying to OHP sheets, etc.,while the tone reproduction is also lowered. The light absorbance at awavelength of 440 nm is more preferably no greater than 0.03, and evenmore preferably no greater than 0.01.

The light absorbance according to the present invention is the valueobtained by dissolving 2 g of the polyester resin in 100 ml of methylchloride, and using a spectrophotometer to measure the absorbance at 440nm.

The main possible cause of the adverse effect on the absorbance of thepolyester resin is that of decomposition products generated duringpolymerization of the polyester resin, and therefore the absorbance maybe lowered by appropriate selection of decomposition-resistant monomersand polymerization conditions which minimize production of decompositionproducts. Since it is particularly important to inhibit production ofaldehyde compounds, their decomposition products and by-products inpolyester resins, it is important that the content of aldehydecompounds, their decomposition products and by-products in polyesterresins and toners be in a range of no greater than 200 ppm, preferablyno greater than 100 ppm, and more preferably no greater than 50 ppm.

The method of obtaining a toner polyester resin according to theinvention is not particularly limited, and it may be obtained, forexample, by the following method.

(1) First, the polymerization components which are an acid component (a)and an alcohol component (b) are charged into a reactor, heated under anitrogen air flow for esterification or transesterification, and then

(2) the water or alcohol produced by the above reaction is removed by acommon method, after which condensation reaction is accomplished under alow temperature of 240° C. or below and a high vacuum of 30 mmHg orlower, while distilling off the aldehyde compounds, their decompositionproducts and by-products, and the alcohol components.

The acid component (a) used to obtain the toner polyester resin of theinvention is one which contains at least one selected from the groupconsisting of aromatic dicarboxylic acids such as terephthalic acid andisophthalic acid, and their lower alkyl esters.

Examples of lower alkyl esters of terephthalic acid and isophthalic acidto be used as the acid component (a) include dimethyl terephthalate,dimethyl isophthalate, diethyl terephthalate, diethyl isophthalate,dibutyl terephthalate, dibutyl isophthalate, etc., and from theviewpoint of cost and handling, dimethyl terephthalate and dimethylisophthalate are preferred. The above-mentioned aromatic dicarboxylicacids and their lower alkyl esters may be used alone or in combinationsof two or more.

The aromatic dicarboxylic acid, having a highly hydrophobic benzenering, is able to both increase the moisture resistance of the toner andincrease the glass transition temperature (hereunder referred to as"Tg") of the resultant resin, thus having an improving effect on theblocking resistance. Thus, the aromatic dicarboxylic acid is preferablypresent at 60 mole percent or greater, and more preferably 70 molepercent or greater, with respect to the total acid component. Sinceterephthalic acid compounds have an effect of increasing both thetoughness and the Tg of the resin, they are preferably present in arange of 50 mole percent or greater, and more preferably 60 mole percentor greater, with respect to the total acid component. Isophthalic acidcompounds, which have an effect of increasing the reactivity, arepreferably used in different usage proportions depending on the desiredobject.

Other examples of dicarboxylic acids which may if necessary be used asthe acid component (a) according to the present invention includephthalic acid, sebacic acid, isodecylsuccinic acid, maleic acid, fumaricacid, adipic acid, and their monomethyl, monoethyl, dimethyl and diethylesters, as well as their acid anhydrides. Since these divalentcarboxylic acid components have a notable effect on the fixing propertyand blocking resistance of the toner, they should be added within arange which does not hinder the object of the invention, preferablyabout 30 mole percent or less with respect to the total acid component,depending on the performance demanded of the resin.

According to the present invention, the acid component (a) used may alsoif necessary be a trivalent or higher polyvalent carboxylic acid.Examples of trivalent or higher polyvalent carboxylic acids includetrimellitic acid, pyromellitic acid, 1,2,4-cyclohexanetricarboxylicacid, 2,5,7-naphthalenetricarboxylic acid,1,2,4-naphthalenetricarboxylic acid, 1,2,5-hexanetricarboxylic acid,1,2,7,8-octanetetracarboxylic acid and their acid anhydrides.

These trivalent or higher polyvalent carboxylic acids may be used eitheralone or in combinations of 2 or more, and for the effect of increasingthe Tg of the resultant resin and the effect of imparting cohesivenessto the resin to increase the non-offsetting property of the toner, theyare preferably used in a range of 0.5 to 30 mole percent, and morepreferably 1 to 25 mole percent, with respect to the total acidcomponent. This is because the above-mentioned effect cannot beadequately achieved at less than 0.5 mole percent, and control ofgelation during production of the polyester resin becomes difficult atgreater than 30 mole percent, which complicates efforts to obtain thedesired resin. When the trihydric or higher polyhydric alcoholsmentioned below are used in combination, the total amount of both ispreferably within the range specified above.

The alcohol component (b) used to obtain the toner polyester resin ofthe present invention contains an aromatic diol comprising a bisphenol Aderivative. Although aromatic diols comprising bisphenol A derivativesresult in production of aldehyde compounds, etc., because of theireffect of raising the Tg of the resin and improving the blockingresistance of the toner, they may be suitably used as alcohol componentsfor the toner polyester resin.

Examples of aromatic diols which may be used according to the inventionare the bisphenol A derivativespolyoxyethylene-(2.0)-2,2-bis(4-hydroxyphenyl)propane,polyoxypropylene-(2.0)-2,2-bis(4-hydroxyphenyl)propane,polyoxypropylene-(2.2)-polyoxyethylene-(2.0)-2,2-bis(4-hydroxyphenyl)propane,polyoxyethylene-(2.3)-2,2-bis(4-hydroxyphenyl)propane,polyoxypropylene-(6)-2,2-bis(4-hydroxyphenyl)propane,polyoxypropylene-(2.3)-2,2-bis(4-hydroxyphenyl)propane,polyoxypropylene-(2.4)-2,2-bis(4-hydroxyphenyl)propane,polyoxypropylene-(3.3)-2,2-bis(4-hydroxyphenyl)propane,polyoxyethylene-(3.0)-2,2-bis(4-hydroxyphenyl)propane,polyoxyethylene-(6)-2,2-bis(4-hydroxyphenyl)propane, etc.

These aromatic diols may be used either alone or in mixtures of 2 ormore. However, since aromatic diols have low reactivity and promotedecomposition, they are a cause of generation of aldehyde compounds,their decomposition pros and by-products, and therefore must be used inlimited amounts in consideration of coloration of the resin and theresulting adverse influence on its absorbance. They are preferably usedin an amount of no more than 90 mole percent, and more preferably nomore than 80 mole percent, with respect to the total acid component.Nevertheless, since the aromatic diol has an effect of raising the Tgand improving the blocking resistance of the toner, it is preferablyused in an amount of at least 20 mole percent with respect to the totalacid component, although the amount must be set for the most favorablebalance against coloration of the polyester resin.

According to the present invention, the alcohol component (b) containsan appropriate amount of an aliphatic diol. Examples of useful aliphaticdiols include ethylene glycol, diethylene glycol, neopentyl glycol,propylene glycol, butanediol, etc., which may be used alone or incombinations of 2 or more. These aliphatic diols have the effect ofimproving the condensation polymerization reaction rate. Of these,ethylene glycol, neopentyl glycol and butanediol are preferred from thestandpoint of the fixing property.

Aliphatic diols impart pliability to the resin and contribute to thefixing property, but because they also lower the Tg and have an adverseeffect on the blocking resistance, they are preferably used in amountsappropriately set depending on the type of machine in which the toner isto be used. The amount of the aliphatic diol is preferably in a range ofbetween 20 and 80 mole percent, and more preferably between 40 and 80mole percent, with respect to the total acid portion.

Furthermore, the alcohol component (b) according to the presentinvention may be, if necessary, a trihydric or higher polyhydricalcohol. Examples of polyhydric alcohols include sorbitol,1,2,3,6-hexanetetrol, 1,4-sorbitan, pentaerythritol, dipentaerythritol,tripentaerythritol, sucrose, 1,2,4-butanetriol, 1,2,5-pentanetriol,glycerol, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol,trimethylolethane, trimethylolpropane, 1,3,5-trihydroxymethylbenzene,etc. These polyhydric alcohols may be used alone or in combinations of 2or more. These trihydric and higher polyhydric alcohols have an effectof increasing the Tg of the resultant resin, while impartingcohesiveness to the resin and increasing the non-offsetting property ofthe toner. They are preferably used in amounts within the range of 0.5to 50 mole percent, and more preferably 1 to 25 mole percent, withrespect to the total acid component. This is because at less than 0.5mole percent the above-mentioned effect is not adequately achieved, andat greater than 30 mole percent it becomes difficult to control gelationof the polyester resin during production, complicating efforts to obtainthe desired resin. When the above-mentioned trihydric or higherpolyhydric alcohols are used in combination, their total amount ispreferably within the ranges specified above.

The toner polyester resin of the present invention may be obtained bypolymerization of the aforementioned acid component (a) and alcoholcomponent (b), but in order to achieve the object of the invention it isessential to employ a polymerization process which minimizes generationof decomposition products which adversely affect coloration of thepolyester resin and can become a cause of irritating odors in the toner.

According to the invention, the aforementioned monomers are charged intoa reactor and heated for esterification or transesterification. At thistime there is also used, if necessary, a publicly known esterificationcatalyst or transesterification catalyst commonly used foresterification or transesterification reactions, such as titaniumbutoxide, dibutyltin oxide, magnesium acetate or manganese acetate.Next, the water or alcohol produced during the reaction is removedaccording to a common method. For the polymerization, a common, publiclyknown polymerization catalyst such as titanium butoxide, dibutyltinoxide, tin acetate, zinc acetate, tin disulfide, antimony trioxide,germanium dioxide, etc., is used.

According to the present invention this is followed by thepolymerization reaction, which may be conducted under a vacuum of 100mmHg or lower while distilling off the diol components. Theesterification reaction, which is the first step of the polymerizationprocess, is preferably conducted under a nitrogen gas flow. Thecondensation reaction, which is the second step, is preferably conductedat a low temperature of 240° C. or lower and a high vacuum of 30 mmHg orlower. When the condensation is carried out at a high temperature ofover 240° C. there is extreme generation of aldehyde decompositionproducts, etc., and resins obtained thereby generate considerableirritating odors when made into toners, and lower the light permeabilitywhen copying is performed with OHP. The temperature for the condensationreaction is more preferably no higher than 230° C., and even morepreferably no higher than 220° C. Also, the high vacuum for the reactionnot only increases the reaction rate, but has the additional effect ofremoving the generated low-boiling-point aldehyde compounds from thesystem. The condensation reaction is more preferably conducted under avacuum of 10 mmHg or lower, and even more preferably 5 mmHg or lower.

The toner polyester resin of the invention which is obtained in thismanner has a content of aldehyde compounds, their decomposition productsand by-products of 200 ppm or lower, is free of coloration, and also haslow light absorbance (at 400 nm), while it does not emanate irritatingodors even upon melting and kneading during the toner production or uponheating during the copying process; thus, it is suitable as a binderresin for full color toner with which tinting of toner images is aparticularly noted problem.

According to the present invention, toner using a binder resin whosemain component is a polyester resin with a content of aldehydecompounds, their decomposition products and by-products of 200 ppm orless, has lower generation of irritating odors of the toner due toaldehyde compounds, their decomposition products and by-products in thetoner. Although the content of aldehyde compounds, their decompositionproducts and by-products in the toner is preferably 200 ppm or less, itis more preferably in the range of 100 ppm or less, and even morepreferably 50 ppm or less.

Furthermore, since the polyester resin of the invention is a resin withhigh light permeability and excellent color tone, having an absorbanceof 0.5 or lower at a wavelength of 440 nm, when it is used as a binderresin for full color toner it is possible to avoid reduction in imageprecision of copied print. Especially when the resin is used as a fullcolor toner binder resin for copying to OHP sheets, etc., it becomespossible to obtain clear images without haziness of the images due tolowered permeability of the copy material, while the range of tonereproduction is also widened, to thus provide superior image precisionfor copied print.

According to the invention, this type of polyester resin is used as themain component of a toner binder resin, but the binder resin may alsoinclude if necessary other resins such as styrene-based resins andstyrene-acrylic reins.

The toner of the invention contains a binder resin whose main componentis the polyester resin described above, and also a coloring agent, withthe binder resin preferably present in the toner within a range of 70 to97 wt %, and more preferably a range of 80 to 95 wt %. This is because abinder resin content of less than 70 wt % tends to reduce thenon-offsetting property of the toner, while a content exceeding 97 wt %tends to impair the electrostatic stability of the toner. Any commoncoloring agent may be used, examples of which are coloring agents andpigments such as carbon black, nigrosine dye, lamp black, Sudan blackSM, navel yellow, mineral fast yellow, lithol red, permanent orange 4R,etc.

The toner of the invention may also include additives such as chargecontrollers, anti-offsetting agents, magnetic powders, etc. Suchadditives may be commonly used ones, examples of which include chargecontrollers such as nigrosine, alkyl-containing azine-based dyes, basicdyes, monoazo dyes and metal complexes thereof, salicylic acid and metalcomplexes thereof, alkylsalicyclic acids and metal complexes thereof,naphthoic acid and metal complexes thereof, etc.; anti-offsetting agentssuch as polyethylene, polypropylene, ethylene-polypropylene copolymer,etc.; magnetic powders such as ferrite, magnetite, etc., and the like.

The toner of the invention is prepared by using a kneading machine suchas a twin-screw extruder or mixer to knead the binder resin, coloringagent and additives at a temperature about 15° to 30° C. higher than thesoftening temperature of the binder resin, and then finely crushing andsorting the product. The resultant toner grains have an average grainsize of preferably about 5-20 μm, and more preferably about 8-15 μm.Fine grains with a grain size of 5 μm or less preferably account forless than 3 wt % of the entirety.

The present invention is explained in more detail below by way ofexamples and comparative examples.

The performance evaluations in the examples and comparative exampleswere made according to the following methods.

(1) Tg (glass transition temperature) (°C.)

A differential scanning calorimeter, product of Shimazu Laboratories,was used for measurement of the melt quenched sample at a temperatureelevation of 5° C./min. The Tg was taken as the intersection (shouldervalue) between the baseline near the endothermic curve and the tangent.

(2) Softening temperature (°C.)

A flow tester (CFT-500), product of Shimazu Laboratories, was used formeasurement of the softening temperature (°C.) as the temperature atwhich half of a 1.0 g sample flowed out under conditions of a 1.0 mmΦ×10mml nozzle, 30 kgf load and a 3° C./min temperature elevation.

(3) Compositional analysis

The resin was hydrolyzed with hydrazine and quantitatively analyzed byliquid chromatography.

(4) Acid value (mgKOH/g)

The resin thermally dissolved in benzyl alcohol and then cooled andtitrated with a 1/50N KOH benzyl alcohol solution.

(5) Content of aldehyde compounds, their decomposition products andby-products

A 2.0 g sample was quantitatively analyzed by headspace gaschromatography (HSS-2B, product of Shimazu Laboratories, KK.)

(6) Organoleptic test

A 10 g sample was placed in a reinforced glass sample bottle and heatedat 150° C. for 30 minutes, after which the presence of odors was noted.

∘: Some irritating odor

x: No irritating odor

(7) Absorbance

A 2 g portion of the resin was dissolved in 100 ml of methylenechloride, and the absorbance at a wavelength of 440 nm was measured witha spectrophotometer (Model 150-20, product of Hitachi Laboratories, KK.)using a standard quartz cell with an optical length of 10 mmL.

(8) Toner image evaluation

A full color copier was used, having a heat roller coated with siliconeoil, a freely variable temperature, and a printing speed of 7 pages/min,and the image haziness and image precision of copying onto OHP film werevisually evaluated according to the following criteria.

⊚: Very clear with no image haziness, and excellent image precision

∘: Clear with almost no image haziness, and satisfactory image precision

x: Conspicuous image haziness and poor image precision

The abbreviations used in the examples and comparative examples standfor the following.

Diol A: polyoxypropylene-(2.3)-2,2-bis(4-hydroxyphenyl)propane

Diol B: polyoxyethylene-(2.3)-2,2-bis(4-hydroxyphenyl)propane

EXAMPLE 1

One hundred molar parts of terephthalic acid, 50 molar parts of diol A,10 molar parts of diol B and 55 molar parts of ethylene glycol werecharged into a reactor equipped with a distillation column. An antimonytrioxide catalyst was added at 0.05 parts by weight to the total acidcomponent, and esterification reaction was conducted under a nitrogenflow at ordinary pressure, maintaining an inner temperature of 260° C.and an agitating rotational speed of 120 rpm. The pressure of thereaction system was then lowered to 1.0 mmHg over a period of 30minutes, and upon condensation reaction for 5 hours while maintaining aninner temperature of 220° C. to distill off the ethylene glycol, therewas obtained resin R-1 with characteristic values of a Tg of 62° C., asoftening temperature of 180° C. and an acid value of 9.3 mgKOH/g. Table1 lists the results of the compositional analysis, quantitative analysisof the aldehyde compound content and organoleptic test for the obtainedresin R-1.

Next, 4 parts by weight of carbon black (#40, product of MitsubishiChemicals, KK.) and 1 part by weight of a charge controller (BontronS-34, product of Orient Chemicals, KK.) were premixed with 94 parts byweight of the above-mentioned resin R-1. An internal mixer (product ofKurimoto Tekko, KK.) was then used for 30 minutes' kneading at 65 rpmwith an internal temperature of 150° C. The resultant kneaded mixturewas coarsely crushed, and then finely crushed and sorted into tonerhaving a grain size of 5-18 μm.

The resultant toner was subjected to quantitative analysis of thealdehyde compound content and organoleptic testing. The results areshown in Table 1.

COMPARATIVE EXAMPLE 1

Esterification and condensation were performed with the same chargedcomposition and procedure for polymerization as in Example 1, to obtainresin R-2. However, during the esterification no nitrogen wasintroduced, and the condensation was conducted at a temperature of 270°C. and a vacuum of 100 mmHg for 6 hours.

The resultant resin R-2 had a Tg of 64° C. and a softening temperatureof 110° C. When the aldehyde compound content of resin R-2 was measured,it was found to contain 350 ppm propionaldehyde. Also, a very strongirritating odor was noted in the organoleptic test.

When toner prepared using this resin R-2 by the same method as inExample 1 was quantitatively analyzed for aldehyde compound content, itwas found to contain 320 ppm propionaldehyde. Also, a strong irritatingodor was noted in the organoleptic test.

When a twin-screw extruder with vent holes was used for the kneadingdescribed above, the propionaldehyde content of the toner was reduced to220 ppm, but an irritating odor was still noted in the organoleptictest.

EXAMPLES 2-7

The same procedure as in Example 1 was followed, except that theesterification atmosphere, condensation conditions and resin compositionwere changed as shown in Table 1, to obtain resins R-3 to R-8.

The resultant resins R-3 to R-8 and toners prepared by the method inExample 1 using these resins R-3 to R-8 were subjected to quantitativeanalysis of aldehyde compounds and organoleptic testing. The results aregiven in Table 1.

All of the resins R-3 to R-8 had low aldehyde compound contents and noirritating odor in the organoleptic test. Their toners also had lowaldehyde compound contents and no irritating odor in the organoleptictest.

COMPARATIVE EXAMPLES 2-5

The same procedure as in Example 1 was followed, except that theesterification atmosphere, condensation conditions and resin compositionwere changed as shown in Table 1, to obtain resins R-9 to R-12.

The resultant resins R-9 to R-12 and toners prepared by the method inExample 1 using these resins R-9 to R-12 were subjected to quantitativeanalysis of aldehyde compounds and organoleptic testing. The results aregiven in Table 1.

All of the resins R-9 to R-12 had high aldehyde compound contents andalso irritating odors in the organoleptic test. Their toners also hadhigh aldehyde compound contents and irritating odors in the organoleptictest.

EXAMPLES 8-9

The same procedure as in Example 1 was followed, except that theesterification atmosphere, condensation conditions and resin compositionwere changed as shown in Table 1, to obtain resins R-13 to R-14.

The resultant crosslinked resins R-13 to R-14 and toners prepared by themethod in Example 1 using these resins R-13 to R-14 were subjected toquantitative analysis of aldehyde compounds and organoleptic testing.The results are given in Table 1.

All of the crosslinked resins R-13 to R-14 had low aldehyde compoundcontents and no irritating odor in the organoleptic test. Their tonersalso had low aldehyde compound contents and no irritating odor in theorganoleptic test.

    __________________________________________________________________________                   Comp.                                                                      Ex. 1                                                                            Ex. 1                                                                             Ex. 2                                                                            Ex. 3                                                                            Ex. 4                                                                             Ex. 5                                                                            Ex. 6                                                                             Ex. 7                                                 R-1                                                                              R-2 R-3                                                                              R-4                                                                              R-5 R-6                                                                              R-7 R-8                                       __________________________________________________________________________    TPA         100.0                                                                            100.0                                                                             100.0                                                                            100.0                                                                            100.0                                                                             100.0                                                                            50.3                                                                              41.1                                      IPA                             49.7                                                                              58.9                                      TMA                                                                           Diol A      49.4                                                                             49.4                                                                              40.2                                                                             30.1                                                                             89.0                                                                              67.7                                                                             30.0                                                                              29.8                                      Diol B      9.8                                                                              9.8 29.8                                                                             30.3      50.3                                                                              29.9                                      Aromatic subtotal                                                                         59.2                                                                             59.2                                                                              70.0                                                                             60.4                                                                             89.0                                                                              67.7                                                                             80.3                                                                              59.7                                      NPG                                                                           EG          41.7                                                                             41.7                                                                              31.2                                                                             42.1                                                                             13.1                                                                              34.3                                                                             21.3                                                                              42.2                                      Aliphatic subtotal                                                                        41.7                                                                             41.7                                                                              31.2                                                                             42.1                                                                             13.1                                                                              34.3                                                                             21.3                                                                              42.2                                      Nitrogen air flow                                                                         ◯                                                                    X   ◯                                                                    ◯                                                                    ◯                                                                     ◯                                                                    ◯                                                                     ◯                             Polymerization temperature                                                                220                                                                              270 200                                                                              180                                                                              230 240                                                                              220 220                                       Vacuum degree                                                                             1  100 1  1  1   30 3   3                                         Polymerization time                                                                       5  6   6  4  6   3  5   2                                         Aldehyde*.sup.1)                                                                          5  350 5  3  23  140                                                                              4   6                                         Organoleptic test                                                                         ◯                                                                    X   ◯                                                                    ◯                                                                    ◯                                                                     ◯                                                                    ◯                                                                     ◯                             Toner aldehyde*.sup.2)                                                                    7  320 3  3  18  135                                                                              5   8                                         Toner organoleptic test                                                                   ◯                                                                    X   ◯                                                                    ◯                                                                    ◯                                                                     ◯                                                                    ◯                                                                     ◯                             __________________________________________________________________________                     Comp.                                                                             Comp.                                                                             Comp.                                                                             Comp.                                                             Ex. 2                                                                             Ex. 3                                                                             Ex. 4                                                                             Ex. 5                                                                             Ex. 8                                                                            Ex. 9                                                      R-9 R-10                                                                              R-11                                                                              R-12                                                                              R-13                                                                             R-14                                      __________________________________________________________________________    TPA              100.0                                                                             100.0                                                                             50.1                                                                              40.2                                                                              56.1                                                                             90.2                                      IPA                              30.1                                         TMA                              13.8                                                                             9.8                                       Diol A           91.2                                                                              50.2                                                                              39.9                                                                              40.1                                                                              50.1                                                                             50.3                                      Diol B               10.1                                                                              21.0                                                                              40.1                                             Aromatic subtotal                                                                              91.2                                                                              60.3                                                                              60.9                                                                              80.2                                                                              50.1                                                                             50.3                                      NPG                      20.1                                                 EG               11.2                                                                              40.7                                                                              21.0                                                                              22.1                                                                              51.1                                                                             51.1                                      Aliphatic subtotal                                                                             11.2                                                                              40.7                                                                              41.1                                                                              22.1                                                                              51.1                                                                             51.1                                      Nitrogen air flow                                                                              X   X   X   X   ◯                                                                    ◯                             Polymerization temperature                                                                     260 280 270 280 240                                                                              220                                       Vacuum degree    50  760 30  100 1  1                                         Polymerization time                                                                            8   12  5   6   2.5                                                                              4                                         Aldehyde*.sup.1) 340 450 310 310 38 58                                        Organoleptic test                                                                              X   X   X   X   ◯                                                                    ◯                             Toner aldehyde*.sup.2)                                                                         320 440 310 295 30 62                                        Toner organoleptic test                                                                        X   X   X   X   ◯                                                                    ◯                             __________________________________________________________________________     TPA: terephthalic acid IPA: isophthalic acid TMA: trimellitic anhydride       NPG: neopentyl glycol EG: ethylene glycol                                     *.sup.1) aldehyde compound (propionaldehyde) content (ppm)                    *.sup.2) aldehyde compound (propionaldehyde) content (ppm) of prepared        toner                                                                    

EXAMPLE 10

One hundred molar parts of terephthalic acid, 60 molar parts of diol Aand 65 molar parts of ethylene glycol were charged into a reactorequipped with a distillation column. An antimony trioxide catalyst wasadded at 0.05 parts by weight to the total acid component, andesterification reaction was conducted under a nitrogen flow at ordinarypressure, maintaining an inner temperature of 260° C. and an agitatingrotational speed of 120 rpm. The pressure of the reaction system wasthen lowered to 1.0 mmHg over a period of 30 minutes, and uponcondensation reaction for 5 hours while maintaining an inner temperatureof 220° C. to distill off the ethylene glycol, there was obtained resinR-15 with characteristic values of a Tg of 64° C., a softeningtemperature of 109° C. and an acid value of 7.1 mgKOH/g. Table 2 liststhe results of the compositional analysis, quantitative analysis of thealdehyde compound content, organoleptic test and absorbance measurementfor the obtained resin R-15.

Next, 5 parts by weight of carbon black (#40, product of MitsubishiChemicals, KK.) and 1 part by weight of a charge controller (BontronS-34, product of Orient Chemicals, KK.) were premixed with 94 parts byweight of the above-mentioned resin R-15. An internal mixer (product ofKurimoto Tekko, KK.) was then used for 30 minutes' kneading at 65 rpmwith an internal temperature of 150° C. The resultant kneaded mixturewas coarsely crushed, and then finely crushed and sorted into tonerhaving a grain size of 5-18 μm.

The resultant toner was subjected to quantitative analysis of thealdehyde compound content and organoleptic testing. The results areshown in Table 2.

COMPARATIVE EXAMPLE 6

Esterification and condensation were performed with the same chargedcomposition and procedure for polymerization as in Example 10, to obtainresin R-16. However, during the esterification no nitrogen wasintroduced, and the condensation was conducted at a temperature of 270°C. and a vacuum of 100 mmHg for 7 hours.

The resultant resin R-16 had a Tg of 63° C. and a softening temperatureof 106° C. When the aldehyde compound content of resin R-16 wasmeasured, it was found to contain 330 ppm propionaldehyde and 40 ppm2-ethyl-1,3-dioxolane, and a very strong irritating odor was also notedin the organoleptic test. The absorbance indicating coloration was0.076.

When toner prepared using this resin R-16 by the same method as inExample 10 was quantitatively analyzed for aldehyde compound content, itwas found to contain 315 ppm propionaldehyde and 37 ppm2-ethyl-1,3-dioxolane, and a strong irritating odor was also noted inthe organoleptic test.

When a twin-screw extruder with vent holes was used for the kneadingdescribed above, the propionaldehyde content of the toner was reduced to220 ppm, but an irritating odor was still noted in the organoleptictest.

EXAMPLES 11-14

The same procedure as in Example 10 was followed, except that theesterification atmosphere, condensation conditions and resin compositionwere changed as shown in Table 2, to obtain resins R-17 to R-20. Table 2also lists the results of the compositional analysis, quantitativeanalysis of the aldehyde compound content, organoleptic test andabsorbance measurement for the obtained resins.

These resins R-17 to R-20 were then used to prepare full color toners inthe same manner as in Example 10, except that a full color tonercoloring agent was used. Table 2 also shows the results of quantitativeanalysis of aldehyde compounds, organoleptic test, absorbancemeasurement and image evaluation for the obtained toners.

All of the resins R-17 to R-20 had low absorbance at a wavelength of 440nm, and exhibited excellent image properties when made into toner.Resins R-19 and R-20 in particular had very excellent image properties.Also, all of the resins R-17 to R-20 had low aldehyde compound contentsand no irritating odor in the organoleptic test. Their toners also hadno irritating odor in the organoleptic test.

COMPARATIVE EXAMPLES 7-10

The same procedure as in Example 10 was followed, except that theesterification atmosphere, condensation conditions and resin compositionwere changed as shown in Table 2, to obtain resins R-21 to R-24. Table 2also lists the results of the compositional analysis, quantitativeanalysis of the aldehyde compound content, organoleptic test andabsorbance measurement for the obtained resins.

These resins R-21 to R-24 were then used to prepare full color toners inthe same manner as in Example 10, except that a full color tonercoloring agent was used. Table 2 also shows the results of quantitativeanalysis of the aldehyde compound content, organoleptic test and imageevaluation for the obtained toners.

All of the resins R-21 to R-24 had high absorbance at a wavelength of440 nm, thus exhibiting poor light permeability, and also gave hazyimages with poor image precision when made into toner. Also, all of theresins had high aldehyde compound contents and irritating odors in theorganoleptic test, and their toners also had irritating odors.

                  TABLE 2                                                         ______________________________________                                                         Comp.                                                                Ex. 10   Ex. 6    Ex. 11 Ex. 12 Ex. 13                                        R-15     R-16     R-17   R-18   R-19                                  ______________________________________                                        TPA     100.0    100.0    100.0  100.0  50.2                                  IPA                                     49.8                                  TMA                                                                           Diol A  59.8     59.8     21.6   72.5   40.3                                  Diol B                    30.3          41.1                                  Aromatic                                                                              59.8     59.8     51.9   72.5   81.4                                  subtotal                                                                      NPG                                                                           EG      48.1     48.1     55.5   38.6   33.3                                  Aliphatic                                                                             48.1     48.1     55.5   38.6   33.3                                  subtotal                                                                      Nitrogen                                                                              ∘                                                                          x        ∘                                                                        ∘                                                                        ∘                         air flow                                                                      Polymeriza-                                                                           220      270      230    220    200                                   tion                                                                          temperature                                                                   Vacuum  1        100      1      1      30                                    degree                                                                        Polymeriza-                                                                           5        7        3      5      5                                     tion time                                                                     Aldehyde*.sup.1)                                                                      11       330      16     25     6                                     Organoleptic                                                                          ∘                                                                          x        ∘                                                                        ∘                                                                        ∘                         test                                                                          Absorbance                                                                              0.007   0.07      0.012                                                                                0.019                                                                                0.009                               (440 nm)                                                                      Toner   10       300      15     22     4                                     aldehyde*.sup.2)                                                              Toner   ∘                                                                          x        ∘                                                                        ∘                                                                        ∘                         organoleptic                                                                  test                                                                          Toner image                                                                           ⊚                                                                       x        ∘                                                                        ∘                                                                        ⊚                      evaluation                                                                    ______________________________________                                                         Comp.    Comp.  Comp.  Comp.                                         Ex. 14   Ex. 7    Ex. 8  Ex. 9  Ex. 10                                        R-20     R-21     R-22   R-23   R-24                                  ______________________________________                                        TPA     49.9     100.0    100.0  80.2   60.2                                  IPA     50.1                     19.8   39.8                                  TMA                                                                           Diol A  20.3     90.0     49.5   39.9   40.1                                  Diol B  50.2              10.3   19.2   40.1                                  Aromatic                                                                              70.5     90.0     59.8   59.1   80.2                                  subtotal                                                                      NPG                              22.1                                         EG      44.2     21.9     50.4   41.0   32.1                                  Aliphatic                                                                             44.2     21.9     50.4   63.1   32.1                                  subtotal                                                                      Nitrogen                                                                              ∘                                                                          x        x      x      x                                     air flow                                                                      Polymeriza-                                                                           180      270      280    250    280                                   tion                                                                          temperature                                                                   Vacuum  3        50       760    30     100                                   degree                                                                        Polymeriza-                                                                           4        8        12     5      6                                     tion time                                                                     Aldehyde*.sup.1)                                                                      4        340      450    210    310                                   Organoleptic                                                                          ∘                                                                          x        x      x      x                                     test                                                                          Absorbance                                                                              0.002    0.073    0.061                                                                                0.034                                                                                0.025                               (440 nm)                                                                      Toner   2        320      410    205    280                                   aldehyde*.sup.2)                                                              Toner   ∘                                                                          x        x      x      x                                     organoleptic                                                                  test                                                                          Toner image                                                                           ⊚                                                                       x        x      ∘                                                                        ∘                         evaluation                                                                    ______________________________________                                         TPA: terephthalic acid                                                        IPA: isophthalic acid.                                                        TMA: trimellitic anhydride                                                    NPG: neopentyl glycol                                                         EG: ethylene glycol                                                           *1: aldehyde compound (propionaldehyde) content (ppm)                         *2: aldehyde compound (propionaldehyde) content (ppm) of prepared toner  

INDUSTRIAL APPLICABILITY

The toner polyester resin according to the present invention has lowlight absorbance and excellent light permeability and color tone, andwhen made into toner it provides excellent image clarity and imageprecision, making it particularly suitable for full color toner withwhich tinting of toner images is a problem. In addition, the polyesterresin and toner according to the invention does not emanate irritatingodors even upon melting and kneading during the toner production or uponheating during the copying process, and is therefore very useful as drytoner resin and toner to be used for electrostatic charged images ormagnetic latent images by electrophotography, electrostatic recording,electrostatic printing, and the like.

We claim:
 1. A toner comprising a binder resin and a coloring agent,wherein a polyester resin is the main component of the binder resin, andthe content of aldehyde compounds, their decomposition products andby-products in the toner is no more than 200 ppm.
 2. Toner according toclaim 1 wherein the content of aldehyde compounds, their decompositionproducts and by-products is no more than 100 ppm.
 3. Toner according toclaim 1 wherein the content of aldehyde compounds, their decompositionproducts and by-products is no more than 50 ppm.
 4. Toner according toclaim 1 wherein the content of aldehyde compounds, their decompositionproducts and by-products is no more than 10 ppm.
 5. Toner according toclaim 1 wherein the aldehyde compounds, their decomposition products andby-products have a boiling point of 180° C. or lower.
 6. Toner accordingto claim 1 wherein the aldehyde compounds, their decomposition productsand by-products have a boiling point of 100° C. or lower.
 7. Toneraccording to claim 1 wherein the aldehyde compounds, their decompositionproducts and by-products have a boiling point of 50° C. or lower. 8.Toner according to claim 1 wherein the aldehyde compounds, theirdecomposition products or by-products are propionaldehyde, acetaldehydeor dioxolane compounds.
 9. The toner of claim 1, wherein the coloringagent is a pigment.
 10. The toner of claim 9, wherein the pigment isselected from the group consisting of carbon black, nigrosine dye, lampblack, Sudan black SM, navel yellow, mineral fast yellow, lithol red andpermanent orange 4R.
 11. The toner of claim 1, comprising 70 to 97% byweight of the binder resin.
 12. The toner of claim 1, wherein thepolyester resin is comprised of an polymerized alcohol component whichcontains at least one bisphenol A derivative diol.
 13. The toner ofclaim 12, wherein the bisphenol A derivative diol is an alkylene oxideaddition product of bisphenol A.
 14. The toner of claim 12, wherein thebisphenol A derivative diol is an ethylene oxide or propylene oxideaddition product of bisphenol A.
 15. A method of making a toner imagecomprising applying the toner of claim 1 to a substrate.
 16. The methodof claim 15, wherein the substrate is a paper or an overhead projectionfilm.
 17. The method of claim 15, wherein the toner is applied to thesubstrate by electrophotography, electrostatic recording orelectrostatic printing.